Mobile communication systems were developed to provide mobile users with communication services. With the rapid advance of technologies, the mobile communication systems have evolved to the level capable of providing high speed data communication service beyond the early voice-oriented services. Recently, standardization for a Long Term Evolution Advanced (LTE-A) system, as one of the next-generation mobile communication systems, is underway in the 3rd Generation Partnership Project (3GPP). LTE-A is a technology designed to provide high speed packet-based communication faster in data rate than the legacy communication technology and aims at commercial deployment around late 2010.
With the evolution of the 3GPP standard, many studies being conducted for optimization of radio networks as well as improvement of data rate. In the mobile communication system, cells having a small service area are used frequently to increase the system throughput and fill coverage holes. The deployment of the small cells is likely to cause frequent handover failure, resulting in mobility management problem. However, there is neither a measure of applying parameters nor development of operation mechanism appropriate for the small cell service area.